Methods of operating and protecting a dishwashing appliance from runaway heating conditions

ABSTRACT

Methods of operating a dishwashing appliance are provided herein. A method may include measuring a temperature at a temperature sensor and identifying a runaway heat condition within a wash chamber based on the measured temperature. The method may also include directing a volume of water to the wash chamber in response to identifying the runaway heat condition and circulating the volume of water within the wash chamber for a recirculation period.

FIELD OF THE INVENTION

The present subject matter relates generally to dishwashing appliances, and more particularly to methods for controlling and managing heat conditions within dishwashing appliances.

BACKGROUND OF THE INVENTION

Dishwashing appliances or dishwashers generally include a tub that defines a wash chamber. Rack assemblies can be mounted within the wash chamber of the tub for receipt of articles for washing. Spray assemblies within the wash chamber can apply or direct wash fluid towards articles disposed within the rack assemblies in order to clean such articles. Multiple spray assemblies can be provided, including, for example, a lower spray arm assembly mounted to the tub at a bottom of the wash chamber; a mid-level spray arm assembly mounted to one of the rack assemblies; or an upper spray assembly mounted to the tub at a top of the wash chamber. Other configurations may be used as well.

It is common to provide dishwashers with one or more heaters in order to supply heat within the wash chamber during one or more of the dishwasher cycles (e.g., during the drying cycle). For example, a rod-type, resistive heating element may be provided, such as the type sold under the name CALROD. Generally, these heating elements include an electric resistance-type wire that is encased in a magnesium oxide-filled, metallic sheath.

Although heaters may be useful for certain dishwashing operations, it is possible for a heater to fail under certain circumstances. A failure condition may occur wherein the heater remains permanently active, or otherwise generates heat for an excessive amount of time (e.g., during a runaway condition). For instance, an electro-mechanical relay on a dishwashers control board may become stuck in an activated or on position. Voltage may thus be supplied to a heater indefinitely. If this occurs, temperatures within the dishwashing appliance may reach damaging levels (e.g., above 110° Celsius). If articles remain within the tub during this time, it is possible for those articles to be damaged along with portions of the dishwashing appliance. In some instances, the failure condition may be unresolvable by a consumer. A user may be required to thus unplug or completely disengage the dishwashing appliance until a trained technician is able to service the dishwashing appliance. Unfortunately, a user is often unaware of the failure condition before damage is done to other portions of the dishwashing appliance or articles therein.

Accordingly, it would be advantageous to provide methods for protecting a dishwashing appliance or articles therein during certain failure conditions.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one exemplary aspect of the present disclosure, a method of operating a dishwashing appliance is provided. The method may include measuring a temperature at a temperature sensor and identifying a runaway heat condition within a wash chamber based on the measured temperature. The method may also include directing a volume of water to the wash chamber in response to identifying the runaway heat condition and circulating the volume of water within the wash chamber for a recirculation period.

In another exemplary aspect of the present disclosure, a method of operating a dishwashing appliance is provided. The method may include measuring a temperature at a temperature sensor and identifying a runaway heat condition within a wash chamber based on the measured temperature. The method may also include directing a volume of water to the wash chamber in response to identifying the runaway heat condition and circulating the volume of water within the wash chamber for a recirculation period. The method may further include draining the volume of water from the wash chamber upon expiration of the recirculation period.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 provides a front view of a dishwashing appliance according to exemplary embodiments of the present disclosure.

FIG. 2 provides a side view of the exemplary dishwashing appliance of FIG. 1.

FIG. 3 provides a front perspective view an internal portion of the exemplary dishwashing appliance of FIG. 2.

FIG. 4 provides a top perspective view of an internal portion of the tub of the exemplary dishwashing appliance of FIG. 3.

FIG. 5 provides a cross-sectional, schematic view of a portion of the exemplary embodiment of FIG. 4 taken along the line 5-5.

FIG. 6 provides a flow chart illustrating a method of operating a dishwashing appliance according to exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

As used herein, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). The terms “first,” “second,” and “third” may be used interchangeably to distinguish one element from another and are not intended to signify location or importance of the individual elements. The terms “upstream” and “downstream” refer to the relative flow direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the flow direction from which the fluid flows, and “downstream” refers to the flow direction to which the fluid flows.

FIGS. 1 through 4 depict an exemplary domestic dishwasher or dishwashing appliance 100 that may be configured in accordance with aspects of the present disclosure. Generally, the dishwashing appliance 100 includes a cabinet 102 having a tub 104 therein that defines a wash chamber 106. The tub 104 includes a front opening and a door 120 hinged at its bottom 122 for movement between a normally closed vertical position (shown in FIGS. 1 and 2), wherein the wash chamber 106 is sealed shut for washing operations, and a horizontal open position for loading and unloading of articles from the dishwasher. In some embodiments, a latch 123 is used to lock and unlock door 120 for access to wash chamber 106.

In some embodiments, upper and lower guide rails 124, 126 are mounted on tub side walls 128 and accommodate roller-equipped rack assemblies 130 and 132. In optional embodiments, each of the rack assemblies 130, 132 is fabricated into lattice structures including a plurality of elongated members 134 (for clarity of illustration, not all elongated members forming assemblies 130 and 132 are shown in FIG. 2). Each rack 130, 132 is adapted for movement between an extended loading position (not shown), in which the rack is substantially positioned outside the wash chamber 106, and a retracted position (shown in FIGS. 1 and 2), in which the rack is located inside the wash chamber 106. This rack movement may be facilitated by rollers 135 and 139, for example, mounted onto racks 130 and 132, respectively. A silverware basket (not shown) may be removably attached to rack assembly 132 for placement of silverware, utensils, and the like that are otherwise too small to be accommodated by the racks 130, 132.

In certain embodiments, dishwashing appliance 100 includes a lower spray-arm assembly 144 that is rotatably mounted within a lower region 146 of the wash chamber 106 and above a tub sump portion 142 so as to rotate in relatively close proximity to rack assembly 132. In exemplary embodiments, such as the embodiment of FIGS. 1 and 2, one or more elevated spray assemblies 148, 150 are provided above the lower spray-arm assembly 144. For instance, a mid-level spray-arm assembly 148 is located in an upper region of the wash chamber 106 and may be located in close proximity to upper rack 130. Additionally or alternatively, an upper spray assembly 150 may be located above the upper rack 130.

The lower and mid-level spray-arm assemblies 144, 148 and the upper spray assembly 150 are part of a fluid circulation assembly 152 for circulating a wash fluid, such as water or dishwasher fluid, in the tub 104. In turn, fluid circulation assembly 152 may provide a flow of wash fluid within the wash chamber 106. For instance, fluid circulation assembly 152 includes a water inlet hose 172 in fluid communication with the wash chamber 106 (e.g., through bottom wall or sidewall of tub 104) to supply water thereto, as generally recognized in the art. The sump portion 142 may thus be filled with water through a fill port that outlets into wash chamber 106. A water supply valve may be provided to control water to the wash chamber 106. Water supply valve may have a hot water inlet that receives hot water from an external source, such as a hot water heater and a cold water input that receives cold water from an external source. It should be understood that the term “water supply” is used herein to encompass any manner or combination of valves, lines or tubing, housing, and the like, and may simply comprise a conventional hot or cold water connection.

In some embodiments, fluid circulation assembly 152 includes a recirculation pump 154 positioned in a machinery compartment 140 located below the tub sump portion 142 (i.e., below a bottom wall) of the tub 104, as generally recognized in the art. The recirculation pump 154 receives fluid from sump 142 to provide a flow to assembly 152 (e.g., via recirculation conduit 156), or a switching valve or diverter (not shown) may optionally be used to select flow. Additionally or alternatively, a separate drain pump 155 may be provided to selectively drain water or wash fluid from sump 142. For instance, drain pump 155, including an exit conduit, may be positioned downstream from sump 142 in fluid communication with wash chamber 104. The exit conduit may extend to a drain outlet. When drain pump 155 is activated, fluid and/or particles within wash chamber 104 may be directed through the exit conduit, flowing wash fluid to an area outside of appliance 100, e.g., an ambient area.

Each spray-arm assembly 144, 148 includes an arrangement of discharge ports or orifices for directing washing fluid received from the recirculation pump 154 onto dishes or other articles located in rack assemblies 130 and 132. The arrangement of the discharge ports in spray-arm assemblies 144, 148 provides a rotational force by virtue of washing fluid flowing through the discharge ports. The resultant rotation of the spray-arm assemblies 144, 148 and the operation of the spray assembly 150 using fluid from the recirculation pump 154 provides coverage of dishes and other dishwasher contents with a washing spray. Other configurations of spray assemblies may be used as well.

In some embodiments, the dishwashing appliance 100 is further equipped with a controller 137 to regulate operation of the dishwashing appliance 100. The controller 137 may include one or more memory devices and one or more microprocessors, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with a cleaning cycle. The memory may represent random access memory such as DRAM or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. For certain embodiments, the instructions include a software package configured to operate appliance 100 and, for example, execute the exemplary method 600 described below with reference to FIG. 6. The memory may be a separate component from the processor or may be included onboard within the processor. Alternatively, controller 137 may be constructed without using a microprocessor (e.g., using a combination of discrete analog or digital logic circuitry, such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software.

The controller 137 may be positioned in a variety of locations throughout dishwashing appliance 100. In the illustrated embodiment, the controller 137 may be located within a control panel area 121 of door 120, as shown in FIGS. 1 and 2. In some such embodiments, input/output (“I/O”) signals may be routed between the controller 137 and various operational components (e.g., pumps 154, 155) of dishwashing appliance 100 along one or more wiring harnesses that may be routed through the dishwashing appliance 100.

Optionally, the controller 137 includes a user interface 136 through which a user may select various operational features and modes and monitor progress of the dishwashing appliance 100. In exemplary embodiments, the user interface 136 may represent a general purpose I/O (“GPIO”) device or functional block. For instance, the user interface 136 may include input components, such as one or more of a variety of electrical, mechanical, or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface 136 may include a display component, such as a digital or analog display device designed to provide visual operational feedback to a user. Additionally or alternatively, the user interface 136 may include one or more audio feedback devices (e.g., speakers) designed to provide audio operational feedback to a user. The user interface 136 may be in communication with the controller 137 via one or more signal lines or shared communication buses. In some embodiments, the user interface 136 is configured to receive one or more alert signals from the controller 137 and, in turn, generate a visual or audio alert response (e.g., at the display device or audio device of the user interface 136).

In additional or alternative embodiments, controller 137 is configured to operably communicate (e.g., wirelessly communicate) with one or more user devices (not pictured), such as a general purpose computer, special purpose computer, laptop, desktop, integrated circuit, mobile device, smartphone, tablet, or other suitable computing device. For instance, controller 137 may be in wireless communication with a user device via a suitable wireless network; such as a local area network (e.g., intranet), wide area network (e.g., internet), low power wireless networks [e.g., Bluetooth Low Energy (BLE)], or some combination thereof and can include any number of wired or wireless links. In general, communication over the network can be carried via any type of wired or wireless connection, using a wide variety of communication protocols (e.g., TCP/IP, HTTP, SMTP, FTP), encodings or formats (e.g., HTML, XML), or protection schemes (e.g., VPN, secure HTTP, SSL).

In some embodiments, a heating element 170 is operably coupled (e.g., electrically coupled or wirelessly coupled) to the controller 137 to selectively provide heat to the wash chamber 106 (e.g., during a drying cycle). For example, heating element 170 may be provided as a resistive heating element 170 mounted to a bottom portion of tub 104. In some such embodiments, heating element 170 is attached to a bottom wall 180 within the sump 142 or wash chamber 106. During use, the controller 137 may thus transmit one or more heating signals (e.g., as an electrical current) in order to activate heating element 170 and initiate the generation of heat therefrom.

In additional or alternative embodiments, a temperature sensor 182 is operably coupled (e.g., electrically coupled or wirelessly coupled) to the controller 137 to selectively transmit one or more temperature signals thereto. In some such embodiments, temperature sensor 182 is mounted to the tub 104 in thermal communication with wash chamber 106. Thus, the temperature signals transmitted to the controller 137 from the temperature sensor 182 may generally correspond to a temperature within the wash chamber 106. As is understood, temperature sensor 182 may be provided as any suitable sensor or a device for detecting temperature and transmitting a corresponding temperature signal therefrom, such as a thermistor, thermocouple, etc.

Generally, the temperature sensor 182 may be mounted in close proximity to the heating element 170. As illustrated especially in FIGS. 3 and 4, the temperature sensor 182 may be positioned beneath heating element 170. In some such embodiments, the temperature sensor 182 is vertically aligned with at least a portion of the heating element 170. Thus, as shown, the temperature sensor 182 may occupy a common vertically-disposed plane with a cross-sectional segment of heating element 170. In certain embodiments, the temperature sensor 182 is mounted to a bottom surface 184 of the bottom wall 180. In other words, the temperature sensor 182 may be located outside the wash chamber 106. For instance, a portion or wall of the tub 104 may be positioned between heating element 170 and the temperature sensor 182 such that heating element 170 is located above an upper or interior surface 186 of a bottom wall 180 of the tub 104 and the temperature sensor 182 is located below the bottom surface 184 of the bottom wall 180 of the tub 104.

Optionally, the temperature sensor 182 may engage or contact the tub 104 (e.g., at the bottom surface 184 thereof). Additionally or alternatively, an insulating jacket 188 (e.g., formed of an insulating foam or polymer) may cover or surround at least a portion of the temperature sensor 182. As shown in FIG. 4, insulating jacket 188 may cover the lateral sides and bottom portion of the temperature sensor 182 such that the temperature sensor 182 is shielded from environmental conditions surrounding the tub 104.

It should be appreciated that the invention is not limited to any particular style, model, or configuration of dishwasher. The exemplary embodiment depicted in the figures is for illustrative purposes only. For example, different locations may be provided for user interface 136, different configurations may be provided for racks 130, 132, different structures or location may be provided for heater 170, different configurations may be provided for fluid assembly 152, and other differences may be applied as well.

Turning now to FIG. 6, exemplary methods (e.g., the method 600) for operating a dishwashing appliance are illustrated. As an example, method 600 may be used to operate any suitable dishwashing appliance. In particular, the method 600 may be used to operate dishwashing appliance 100 (FIG. 1). The controller 137 (FIGS. 2, 3, and 4) may be programmed or otherwise configured to implement some or all of the method 600.

Advantageously, the present methods may serve to prevent excessive temperatures from being reached within the wash chamber of a dishwashing appliance, such as during one or more failure modes or runaway conditions. Additionally or alternatively, the present methods may advantageously prevent excessive temperatures within a dishwashing appliance without relying on complex or single use components that may be costly to maintain or replace.

At 610, the method 600 includes measuring a temperature at the temperature sensor. For example, the temperature sensor mounted to the tub may transmit a temperature signal to the controller, which is configured to interpret the received temperature signal as a corresponding temperature value. In some embodiments, 610 occurs during a portion of a washing operation for the dishwashing appliance (e.g., a wash cycle). In additional or alternative embodiments, 610 occurs during an idle state of the dishwashing appliance following a wash cycle.

As is understood, the idle state corresponds to a period in which no water is being actively directed to or recirculated through the wash chamber. For example, the idle state may correspond to a drying cycle wherein the heating element is activated to generate heat within the wash chamber. As another example, the idle state may correspond to a period of time following completion of a washing operation (e.g., when no further wash cycles or drying cycles have been initiated or are otherwise anticipated at the controller).

At 620, the method 600 includes identifying a runaway heat condition within the wash chamber of the dishwashing appliance. In particular, the identification at 620 may be based on the measured temperature at 610. The identification at 620 may be initiated in response to the measured temperature alone (i.e., solely in response to measuring the temperature at 610) or, alternatively, in response to the measured temperature in conjunction with one or more previously measured temperatures (e.g., after multiple temperature measurements have been obtained from the temperature sensor). In some embodiments, 620 includes comparing the measured temperature at 610 to a predetermined temperature threshold (e.g., threshold value). Optionally, the predetermined temperature threshold may be between 70° Celsius and 110° Celsius, between 75° Celsius and 100° Celsius, or between 80° Celsius and 90° Celsius. For instance, the predetermined temperature threshold may be 82° Celsius. After comparing the measured temperature to the predetermined temperature threshold, a determination may be made as to whether the predetermined temperature threshold is exceeded. In other words, 620 may include determining the measured temperature equals or exceeds the predetermined temperature threshold. In some such embodiments, equaling or exceeding the predetermined temperature threshold generally indicates that a runaway heat condition has been assumed or reached within the wash chamber.

At 630, the method 600 includes directing a volume of water to the wash chamber in response to identifying the runaway heat condition. For instance, the dishwashing appliance may open the water supply valve (e.g., for a predetermined period of time or until a predetermined measured volume of water is present within the wash chamber).

At 640, the method 600 includes circulating the volume of water within the wash chamber for a recirculation period. As described above, a pump assembly of the dishwashing appliance may be activated such that water flows to and from one or more of the spray assemblies before being returned to the wash chamber and again recirculated. In certain embodiments, the recirculation period is a predetermined time period (e.g., during which the pump assembly will remain active to draw water from the wash chamber and directed to one or more of the spray assemblies).

At 650, the method 600 includes draining the volume of water from the wash chamber upon expiration of the recirculation period. In some such embodiments, one or more pump assembly, such as the drain pump described above, a be activated such that the volume of water within the wash chamber is removed therefrom and, in some instances, out of the dishwashing appliance.

In optional embodiments, the method 600 includes halting power to the heater or resistive heating element in response to identifying the runaway heat condition at 620. For instance, power may be halted to the resistive heating element prior to 650. The controller may transmit a separate restriction signal to the resistive heating element or, alternatively, stop an active heating signal from being transmitted to the resistive heating element. Optionally, power may be halted in tandem with or during at least a portion of 640.

In additional or alternative embodiments, the method 600 may include transmitting an alert signal in response to identifying the runaway heat condition at 620. As an example, a visual alert signal or audio alert signal may be transmitted to the user interface of the dishwashing appliance. As another example, a remote alert signal may be wirelessly transmitted to a separate user device (e.g., cell phone, tablet, personal computer, etc.), as would be generally understood. The alert signal may be transmitted prior to 650 or 640. Optionally, transmission of the alert signal may immediately follow or be an immediate response to 620.

In further additional or alternative embodiments, the method 600 may include repeating one or more of the above steps. For instance, the measured temperature at 610 may be a first temperature. The method 600 may provide for measuring a second temperature (e.g., at the temperature sensor subsequent to the measurement of the first temperature). In some such embodiments, the second temperature is measured following 650. Repetition of one or more steps may generally provide for multiple determinations of runaway heat condition. In other words, the dishwashing appliance may determine if or runaway condition has persisted or abated following execution of steps 610 through 650.

In certain embodiments, the runaway heat condition determined at 620 is a first runaway heat condition, the volume of water at 630 is a first volume of water, and the recirculation period at 640 is a first recirculation period. Following 650, a second runaway heat condition within the wash chamber may be determined (e.g., based on a second measured temperature). In response to identifying the second runaway heat condition, the method 600 may include directing a second volume of water to wash chamber. The second volume of water may be equal to or greater than the first volume of water at 630. Once the second volume of water has reached the wash chamber, the method 600 may further include circulating the second volume of water within the wash chamber (e.g., for a second recirculation period that is less than, equal to, greater than first recirculation period).

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A method of operating a dishwashing appliance comprising a tub defining a wash chamber, the dishwashing appliance further comprising a temperature sensor mounted to the tub, the method comprising: measuring a temperature at the temperature sensor; identifying a runaway heat condition within the wash chamber based on the measured temperature; directing a volume of water to the wash chamber in response to identifying the runaway heat condition; and circulating the volume of water within the wash chamber for a recirculation period.
 2. The method of claim 1, wherein measuring the temperature occurs during an idle state of the dishwashing appliance following a wash cycle.
 3. The method of claim 1, wherein identifying the runaway heat condition comprises comparing the measured temperature to a predetermined temperature, and determining the measured temperature equals or exceeds the predetermined temperature threshold.
 4. The method of claim 1, wherein the recirculation period is a predetermined time period.
 5. The method of claim 1, further comprising draining the volume of water from the wash chamber upon expiration of the recirculation period.
 6. The method of claim 5, wherein the measured temperature is a first temperature, and wherein the method further comprises measuring a second temperature subsequent to draining the volume of water.
 7. The method of claim 6, wherein the runaway heat condition is a first runaway heat condition, wherein the volume of water is a first volume of water, wherein the recirculation period is a first recirculation period, and wherein the method further comprises: identifying a second runaway heat condition within the wash chamber based on the second measured temperature; directing a second volume of water to the wash chamber in response to identifying the second runaway heat condition; and circulating the second volume of water within the wash chamber for a second recirculation period.
 8. The method of claim 1, wherein the dishwashing appliance further comprises a resistive heating element mounted to the tub within the wash chamber.
 9. The method of claim 8, wherein the temperature sensor is positioned beneath the resistive heating element in vertical alignment therewith.
 10. The method of claim 9, wherein the temperature sensor is mounted to a bottom surface of the tub outside of the wash chamber.
 11. The method of claim 9, further comprising: halting power to the resistive heating element in response to identifying the runaway heat condition.
 12. The method of claim 1, further comprising: transmitting an alert signal in response to identifying the runaway heat condition.
 13. A method of operating a dishwashing appliance comprising a tub defining a wash chamber, a temperature sensor mounted to the tub, a resistive heating element positioned above the temperature sensor in thermal communication with the wash chamber, the method comprising: measuring a temperature at the temperature sensor; identifying a runaway heat condition within the wash chamber based on the measured temperature; directing a volume of water to the wash chamber in response to identifying the runaway heat condition; circulating the volume of water within the wash chamber for a recirculation period; and draining the volume of water from the wash chamber upon expiration of the recirculation period.
 14. The method of claim 13, wherein the recirculation period is a predetermined time period.
 15. The method of claim 13, wherein the measured temperature is a first temperature, and wherein the method further comprises measuring a second temperature subsequent to draining the volume of water.
 16. The method of claim 15, wherein the runaway heat condition is a first runaway heat condition, wherein the volume of water is a first volume of water, wherein the recirculation period is a first recirculation period, and wherein the method further comprises: identifying a second runaway heat condition within the wash chamber based on the second measured temperature; directing a second volume of water to the wash chamber in response to identifying the second runaway heat condition; and circulating the second volume of water within the wash chamber for a second recirculation period.
 17. The method of claim 13, wherein the temperature sensor is mounted to a bottom surface of the tub outside of the wash chamber.
 18. The method of claim 13, further comprising: halting power to the resistive heating element in response to identifying the runaway heat condition.
 19. The method of claim 13, further comprising transmitting an alert signal in response to identifying the runaway heat condition. 